The invention pertains to a single facer apparatus for forming a single face web of corrugated paperboard. More particularly, the invention relates to a corrugating roll assembly comprising a large diameter corrugating roll (i.e. a bonding roll) and a small diameter corrugating roll in which the support arrangement for the small diameter roll is also utilized to drive the corrugating roll pair.
In the manufacture of corrugated paperboard, a single facer apparatus is used to corrugate the medium web, to apply glue to the flute tips on one face of the corrugated medium web, and to bring a liner web into contact with the glued flute tips of the medium web with the application of sufficient heat and pressure to provide an initial bond. For many years, conventional single facers have typically included a pair of fluted corrugating rolls and a pressure roll, which are aligned so that the axes of all three rolls are generally coplanar. The medium web is fed into a corrugating nip formed by the interengaging corrugating rolls. While the corrugated medium web is still on one of the corrugating rolls, adhesive is applied to the flute tips by a glue roll. The liner web is immediately thereafter brought into contact with the adhesive-coated flute tips and the composite web then passes through the nip formed by the corrugating roll and the pressure roll.
In the past, the fluted corrugating rolls have typically been generally the same size. More recently, a significantly improved single facer apparatus has been developed in which the corrugating rolls comprise a large diameter bonding roll and a substantially smaller diameter roll, with the ratio of diameters being 3:1 or greater. Such apparatus is disclosed in U.S. Pat. Nos. 5,628,865, 5,951,816, and 6,012,501, all which disclosures are incorporated herein by reference. In accordance with these disclosures, the single facer typically includes a backing arrangement for the small diameter corrugating roll. One preferred backing arrangement includes a series of axially adjacent pairs of backing idler rollers, each pair having a backing pressure belt entrained therearound. Each of the pressure belts is positioned to bear directly against the fluted surface of the small diameter corrugating roll on the side of the small corrugating roll opposite the corrugating nip. Each pair of associated idler rolls and pressure belts is mounted on an actuator, and can thus engage the small diameter corrugating roll with a selectively adjustable force. The application of force against the small diameter corrugating roll, in turn, applies force along the corrugating nip between the small diameter roll and the large diameter roll and along the full length of the nip. Typically, a force of approximately 100 lbs. per linear inch (e.g. 10,000 lbs. for a 100 inch roll) is desirable for properly fluting a medium web at typical line speeds.
In my co-pending application Ser. No. 10/000,514, filed on Oct. 23, 2001 and entitled xe2x80x9cSingle Facer with Quick Change Rollsxe2x80x9d, a single facer apparatus is disclosed in which three matching pairs of large diameter and small diameter corrugating rolls may be easily interchanged. In that apparatus, the interchangeable large diameter corrugating rolls are carried on a rotatable turret and the small diameter corrugating rolls are supplied from a storage magazine positioned laterally offset from the turret and the single facer machine. Because the large diameter corrugating rolls also function as heated bonding rolls, they are supplied with steam and must also be provided with a facility to collect and return the condensate. The large diameter bonding roll is typically directly driven and, in my improved apparatus with three large diameter bonding rolls mounted on a turret, driving the single facer with a direct drive to the large diameter bonding roll provides a complicated and challenging engineering problem. Likewise, an attempt to provide a direct drive to the small diameter corrugating roll, which has to be replaced to match the repositioning of a new large diameter bonding roll, would also be complex and difficult.
Thus, some other means of driving the single facer corrugating rolls would be most desirable.
In accordance with the present invention, the pressure belt arrangement for supporting the small diameter corrugating roll also provides rotatable drive to the small diameter roll from which driving rotation is transmitted through the nip to the large diameter corrugating roll.
In a single facer apparatus in which a single face corrugated web is formed, which apparatus includes a large diameter fluted corrugating roll, a small diameter fluted corrugating roll that is positioned to interengage the large diameter roll to create a corrugating nip, a plurality of backing roll arrangements positioned in operative rotatable engagement with the small diameter corrugating roll, each of which backing roll arrangements includes pairs of backing rolls mounted on a support assembly and a pressure belt entrained around each pair of backing rolls, and an actuator arrangement that is operatively connected to the support assemblies to impose a variable backing force on the backing roll arrangements to force the pressure belts into contact with the small diameter corrugating roll; the improvement provided by this invention comprises a drive arrangement that includes a common drive connection to one of the rolls of each backing roll pair; a source of motive power operatively connected to the drive connection to rotatably drive the commonly connected backing rolls; and, said actuator arrangement being operative to transmit a backing force to the pressure belts and the small diameter corrugating roll sufficient to transmit driving rotation from the small diameter roll through the nip to the large diameter corrugating roll.
Preferably, the commonly connected backing rolls are arranged coaxially along a common axis of rotation and the drive arrangement comprises a drive shaft disposed on the common axis and connected to the source of motive power. In this embodiment, the commonly connected backing rolls comprise toothed sheaves fixed to the drive shaft, and the pressure belts are provided with toothed inner faces for driving engagement with the backing rolls. In the preferred embodiment, each of the commonly connected backing rolls supports a plurality of axially adjacent pressure belts. The actuator arrangement preferably comprises an actuator for each of the backing rolls that forms the other of said backing roll pairs.
The method of driving a single facer, in accordance with the present invention, includes the steps of (1) providing one of the rolls of each backing roll pair with a common rotatable drive connection, (2) driving the drive connection to rotatably drive the commonly connected backing rolls and the pressure belts entrained thereon, (3) supporting the backing rolls and pressure belts to apply a selectively variable radial backing force to the small diameter corrugating roll, and (4) applying a radial force sufficient to transmit driving rotation a small diameter corrugating roll and through the nip to the large diameter corrugating roll.
The method preferably includes the steps of mounting the commonly connected backing rolls coaxially on a common axis of rotation, and rotatably interconnecting said commonly connected backing rolls with a drive shaft disposed on the common axis. The method further includes the step of providing the commonly connected backing rolls and the pressure belts with a toothed interface for positive driving engagement. The method further comprises the step of supporting a plurality of axially adjacent pressure rolls on each of said commonly connected backing rolls.